Retain infrastructure names and share/mount roots behind policy switches

Add a `retain` block to privacy_policy.json (all on by default) so assessments
show software, services, processes, tasks, shares/mounts and private peer IPs.
Values pass an identifier-pattern filter (digit runs, SSN/phone, e-mail, charset,
length, path depth). Accounts, command lines, child paths, filenames and public
peer IPs stay omitted. Linux collector and Windows PowerShell collectors updated;
tests cover retention, withholding and all-switches-off.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

tests/test_import.py

@@ -23,7 +23,7 @@ class ImportTests(unittest.TestCase):
         data = self.load(collect_demo(LINUX_DEMO_HOST))
         self.assertEqual(data['server']['platform'], 'linux')
         result = assess(data)
-        self.assertTrue(any('Share-' in item['evidence'] for item in result['findings']))
+        self.assertTrue(any('Configured non-administrative share' in item['evidence'] for item in result['findings']))
         self.assertTrue(any('certificates:' in item['evidence'] for item in result['findings']))
 
     def test_report_wrapper_recomputed_and_sensitive_fields_removed(self):